Twenty-five countries have pledged $100 million in aid to Venezuela, a top US official said Thursday, as the crisis-hit country's Supreme Court took aim at oil executives appointed by the opposition.

Venezuela is plagued by hyperinflation and major shortages of basic goods, and two men -- opposition leader Juan Guaido and President Nicolas Maduro -- are vying for control of the country.

The United States is among more than 50 countries that have recognized Guaido as interim president, but Maduro -- backed by the country's military as well as Russia, China and dozens of other states -- has so far refused to relinquish his office.

US national security advisor John Bolton made the announcement on the aid pledged to Venezuela following an Organization of American States conference on assisting the country.

"Today, 25 countries, united at the OAS-hosted Conference on Humanitarian Assistance in Support of Venezuela pledged $100 million in humanitarian assistance," Bolton tweeted.

According to David Smolanksy, coordinator of an OAS working group on migration and refugees from Venezuela, the money will go directly to aid collection centres set up on the borders with Colombia and Brazil and on the Caribbean island of Curazao.

At the opening of the conference in Washington, Guaido's representative in the United States, Carlos Vecchio, said the priority is to get aid into Venezuela on February 23 -- a month after Guaido declared himself Venezuela's interim president.

Blockade at the border

Guaido and Maduro have been locked in a battle over allowing aid into the country, and the military reinforced a blockade on Thursday at the border with Colombia, where the opposition leader has vowed to bring in desperately-needed goods.

AFP journalists saw several new freight containers blocking the road that connects the town of Urena in Venezuela to Cucuta in Colombia, where tons of US aid has been piling up for a week.

Venezuela is enduring the biggest economic crisis in its modern history, with hyperinflation predicted to hit 10 million per cent this year according to the International Monetary Fund.

On Wednesday, the opposition-controlled National Assembly -- which is headed by Guaido -- appointed executives to form new boards for Venezuelan state oil firm PDVSA and its US-based affiliate Citgo.

Venezuela's Supreme Court took aim at the move the following day, ordering that the new appointees face criminal prosecution.

The high court -- which is packed with Maduro loyalists -- ruled that the executives were named by a legislature whose decisions are "null," and that the appointees should face prosecution for crimes including "usurpation," "corruption," "organized crime" and "terrorism."

The Supreme Court decision set in motion the process of extraditing the accused, most of whom are in the United States, and freezing their accounts.

Guaido celebrated the appointments as a "step forward in the reconstruction of PDVSA," but Maduro had warned that those accepting "illegal" appointments would face justice.

The United States, which is leading the push to topple Maduro, has sanctioned key regime financial assets including the Citgo subsidiary, and President Donald Trump has refused to rule out military action against the leftist leader.

Story highlights

Venezuela is enduring the biggest economic crisis in its modern history, with hyperinflation predicted to hit 10 million per cent this year according to the International Monetary Fund.